Abstract
This case report presents the application of FOLactis, a lactic acid bacterium in situ vaccine, in the treatment of a lung adenocarcinoma patient who presented with malignant pleural effusion (MPE). An adult patient diagnosed with lung adenocarcinoma complicated by malignant pleural effusion (MPE) experienced favorable outcomes following the administration of intracavitary infusion of FOLactis, as conventional therapeutic approaches failed to yield satisfactory results. One month after the administration of FOLactis treatment, a subsequent CT examination revealed the complete resolution of malignant pleural effusion (MPE).